Kepler's Laws

You could imagine that the orange object
shown here is a satellite going round the earth ( shown in
blue ). You can vary the eccentricity of its orbit and
observe the motion. You should be able to notice the change
in the velocity vector as the satellite goes around the earth.

The graph on the right is plot of kinetic energy (red), potential Energy (blue) and total energy (yellow) versus time. You
should be able to notice that total energy is a constant. You
should also be able to notice that when e=0, the orbit is
circular and all energies are constant and kinetic energy is
half of the modulus of potential energy.